Pigmented vinylidene plastics and method for preparing the same



United States Patent PIGMEN'IED VINYLIDENE PLASTICS AND METHOD FORPREPARING THE SANIE Vincent C. Vesce, Smoke Rise, Kinnelon, N. J.,assignor to The B. F. Goodrich Company, New York, N. Y., a corporationof New York No Drawing. Application June 2, 1953, Serial No. 359,221

14 Claims. (Cl. 260-41) This invention relates to pigmented compositionsand more particularly relates to the production of pigmentedcompositions of matter suitable for the coloring of plastics generallyand specifically in the present application to the pigmentation of oneof the classes of plastics, namely, vinylidene resin plastics, disclosedin my prior application Serial No. 108,423, filed August 3, 1949, now U.S. Patent 2,649,382, of which this present application is acontinuation-in-part.

The production of plastic masses containing dispersed pigment forincorporation into large batches for coloring purposes is not broadlynew. Such dispersions are known in the industry as color master batches.In the production of vinylidene resin plastic color master batchesheretofore it has been necessary to submit pigment and plastic toprolonged and expensive mechanical working in equipment capable ofexerting high shearing stresses in order to achieve a dispersion ofpigment in plastic of moderately satisfactory quality. In such prioroperations, the milling times are considerable, the power requirementsfor such equipment very high, the constant attendance of skilled laboris required, and the degree of dispersion obtained leaves much to bedesired when a very fine degree of dispersion is required.

I have discovered that vinylidene resin plastic color master batches ofextremely high quanlity can be prepared in an efficient manner withsimple inexpensive milling of pigment and vinylidene resin plastic bythe use of a novel and special type of liquid grinding medium, whichlater can be easily removed from the milled batch, and even reused, ifdesired, for new batches. After the removal of the liquid grindingmedium from the milled batch, the dispersed pigment-in-plastic solidsare dried, the dried vinylidene resin plastic master color batch beingnormally in a free-flowing particulate form, which is soft in textureand can be easily reduced to a very fine powdery consistency.

The vinylidene resin plastic master color batches produced in the novelprocess above recited are stable, uniform and free from agglomerates,have a high chromaticity, and, when used to color plastic masses, makeavailable the full strength of the pigment employed.

One object of this invention is the production of a vinylidene resinplastic master color batch, which requires only simple, inexpensivemilling in its preparation. Another object is the production of apigmented vinylidene resin plastic containing solid pigment in a stateof extremely fine and uniform dispersion and having a high chromaticity.Still another object is the production of a uniformly fine dispersion ofsolid pigment in vinylidene resin plastic in the form of a' dry,free-flowing powder which is easily incorporated into a mass of the sameor similar plastic to give a uniformly colored plastic mass capable ofbeing spun, extruded, molded or treated in any of the many ways known tothose skilled in the art of utilizing such pigmented vinylidene resinplastics for the production of uniformly and strongly colored yarns,

2,786,822 Patented Mar. 26, 1957 filaments, films, lacquers, paints,enamels, and other products.

Further objects of this invention will be apparent from the detailedspecifications which follow.

In practicing the invention of this application, I place in a ball,pebble or other colloidal mill a mixture con sisting essentially of thevinylidene resin plastic to be pigmented, the specific pigment, and thenovel liquid grinding medium comprising water and a liquid organicsolvent for the vinylidene resin plastic to be pigmented characterizedadditionally by its water-miscibility. Both the plastic and the pigmentmay be in particulate form.

The organic solvent and water are present in the novel liquid grindingmedium in such proportions that the liquid grinding medium does notdissolve a substantial amount of the plastic and does not causesubstantial agglomeration of the plastic. The balls or pebbles or othersolid grinding elements are added to the mixture of plastic, pigment andliquid grinding medium, the mill closed and allowed to grind themixture, without necessity for any attendant, until a dispersion ofpigment in plastic of the desired degree is obtained.

The vinylidene resin plastics which are embodied in the specification asillustrative of the invention of this application .are vinylidene resinplastics of normally solid structure, substantially insoluble in waterand at least partially soluble in an organic solvent which is misciblewith water. Such a plastic is hereinafter in this specification and inthe appended claims termed a vinyl resin plastic. Many vinylidene resinplastics, but by no means all such vinylidene resin plastics, areenumerated and classified in volume 5, chapter 1 of Protective andDecorative Coatings, edited by Joseph I. Mattieilo, Ph. D., andpublished in 1946 by John Wiley & Sons, Inc., of New York.

On page 4 and pages 44 through 49, of the aboveidentified publication,Mattiello enumerates the types of vinylidene compounds which come withinthe term vinylidene resin plastic as herein employed as including thepolyalkanes, such as the polymers of ethylene and of isobutene; thehalogenated polyalkanes and polyalkenes, such as the polymers of vinylchloride, of vinylidene chloride and of chloroprene; the polyarylenes,such as the polymers of styrene; the vinylidene resin plasticscontaining oxygen, such as the polymers of vinyl acetate, of vinylacetal, of the acrylates, the methacrylates and methyl methacrylates;and copolymers of vinylidene compounds. The vinylidene resin plasticshereinabove listed, which were incorporated by reference in theaforementioned parent application, Serial No. 108,423, are recited inthis specification as including some of the vinylidene resin plasticssuitable for the purpose of this invention.

It is apparent from an examination of the polyvinylidene compoundsrecited in the preceding paragraph that the vinylidene resin plastics ofthis application are the polymerization products of monomers having thegeneral formula H R! 11/ R2 herein referred to as vinylidene monomers aswell as the copolymerization products of such vinylidene monomers withother monomers of the same type and/or with other organic compounds. 7

By way of illustration only of the vinylidene monomers embraced by theabove indicated formula and of the vinylidene resin polymers thereof,the following examples are given:

(a) Where R1 and R2 represent the same element or radical, if each R1and R2 is hydrogen, then the monomer is ethylene and the vinylideneresin plastic is polyethyl- 3 ene; if each. R1v and R2 is chlorine, thenthe monomer is vinylidene chloride and the vinylidene resin plastic ispolyvinylidene chloride known in the trade as Saran; if each R1 and R2is a methyl radical, then the monomer is isobutylene and the vinylideneresin plastic is polyisobutylene, known in the trade as Vistenex;

([2) Where R1. represents a hydrogen atom and R2 represents anotherelement or a radical, if R2 is a chlorine atom, then the monomer isvinyl chloride and the vinylidene resin plastic is polyvinyl chloride,known in the trade as Geon; if R2 is an acetate radical, then themonomer is vinyl acetate and the vinylidene resin plastic is polyvinylacetate; if & is a phenyl radical, then the monomer is styrene and thevinylidene resin plastic is polystyrene, known in the trade as Lustron;if R2 is a CN radical, then the monomer is acrylonitrile and thevinylidene resin plastic is polyacrylonitrile, known in the trade asOrlon; if R2 is a COOCHs radical, then the monomer is methyl acrylateand the vinylidene resin plastic is polymethyl acrylate, known in thetrade as Acryloid; if R2 is a carbazole radical, then the monomer isvinyl carbazole and the vinylidene resin plastic is polyvinyl carbazole,known in the trade as Polectron.

(c) Where R1 and R2 represent different radicals, if R1 is a CH3 radicaland R2 21 COOCH3 radical, then the monomer is methyl methacrylate andthe vinylidene resin plastic is polymethyl methacrylate, known in thetrade as Plexiglas and Lucite.

Further, the vinylidene resin plastics of this invention may be producedby the copolymerization of any two of the monomers of the aboveindicated general formula, thus, copolymerization of vinyl chloride andvinylidene chloride produces a vinylidene resin plastic known in thetrade as Geon; copolym-erization of vinyl chloride and vinyl acetateproduces a vinylidene resin plastic known in the trade as Vinylite andTygon; copolymerization of vinyl chloride and acrylonitrile produces avinylidene resin plastic known in the trade as Dynel or Vinyon N;copolymerization of acrylonitrile and vinyl acetate produces avinylidene resin plastic known in the trade as Acriian; copolymerizationof vinylidene chloride and acrylonitrile produces a vinylidene resinplastic known in the trade as Saran.

It is to be understood that the above enumerated polymers and copolymersare given by way of illustration only of the class of vinyl compoundscomprehended within the term vinylidene resin plastic as that term isdefined hereinabove and is employed in this specification and in theappended claims.

As pigment, one may employ any of the solid colorants normally used inthe industry for the coloring, opacifying, delustering or otherwisemodifying the color of the vinylidene resin plastics. These include theinorganic prime pigments, organic prime pigments, various inert orextender pigments, metallicpigments and the various finely dividedcarbon blacks, including bone and gas blacks, such as disclosed inMattiello Protective and Decorative Coatings, volume 2, chapter 1(1942), or the Journal of the Society of Dyers and Colorists, volume 61(307), December 1945.

As an essential feature of the invention, the vinylidene resin plasticand pigment are mixed with a liquid grinding medium comprising water anda liquid organic watermiscible solvent for the plastic employed. It isimportant that the mixture of Water and solvent be present in suchproportions in the liquid grinding medium that, during the time ofprocessing, the mixture of liquid organic solvent and water does notsubstantially dissolve the vinylidene resin plastic or substantiallycause it to gell or agglomerate.

To accurately find the point at which the liquid organic solvent andwater liquid grinding medium becomes substantially a non-solvent for thevinylidene resin plastic, a series. of test specimens are made upcomprising the. selected solvent with various percentages of water. Suchp in an amount of about 1 part of vinylidene resin plastic to 4 parts ofliquid medium. The mixture is well agitated and the vinylidene resinplastic is then permitted to settle.

One may note that in one or more of the bottles the vinylidene resinplastic either goes completely into solution or clumps or agglomeratesint-o a more or less translucent, gell-like mass. It will also be notedthat in the remaining bottles, the plastic retains a discrete particleappearance. While these effects can generally be observed almostimmediately, it is better to permit about 4 hours of contact beforecomparisons are made and still more preferably one may allow as muchtime for contact as is to be given during the actual pigment dispersionoperation.

The action of the mixture of water and liquid organic solvent on thevinylidene resin plastic when it is less drastic than that which causesa gelling and agglomeration of the vinylidene resin plastic and yetcontains suflicient solvent to make the vinylidene resin plasticreceptive to pigment dispersion can best be termed a pigment receptiveaction on the plastic.

The most desirable and optimum water-organic solvent liquid grindingmedium has been found to be the one having that proportion of water justsufiicient to prevent the above-mentioned extensive solvent action, andyet have enough solvent present to attack the vinylidene resin plasticand make it receptive to the entrance and dispersion of pigment. Itshould be clearly understood, however, that for operability there is noprecise percentage of solvent in water or precise point where the liquidmedium imparts the receptive quality to the vinylidene resin plasticbut, rather, a range which may vary from about 2 or 3 percentin the caseof particular solvents and particular vinylidene resin plasticsto asmuch as about with other solvents and vinylidene resin plastics. Theindication that the amount of solvent is approximately below that whichresults in gelling or agglomeration is. intended to cover that rangewhere the pigment receptive action on the vinylidene resin plastic takesplace.

The amount of liquid grinding medium comprising liquid organic solventand water, used in the process, is selected by the operator to besufiicient to give fluidity to the solids in the particular mill used inthe process. A mill with Flint pebbles, for example, will generallyrequire more liquid grinding medium than one using steel balls. It is,of course, obvious that one may, if so desired, use other types of millsfor the grinding operation.

Such liquid organic water-miscible solvents which will solubilize thevinylidene resin plastics include the alcohols, as, for example, methyl,ethyl, iso-propyl alcohol, diacetone alcohol, etc.; dioxane; the glycolothers as, for example, the Cellosolves and the Carbitols; the esterssuch as the Cellosolve acetates and methyl or ethyl lactate; the ketonessuch as acetone, methyl-ethyl ketone; and other solvents or mixture ofsolvents for the vinylidene resin plastics well known to the art.

For a better understanding of the invention, the following examples aregiven, it being clearly understood that these are merely by way ofillustration and not to be considered limitative of the invention.References to. the pigments employed utilize the generally acceptedtrade name. The letter M with figure and page number following the namerefers to the figures and pages in volume 5 of J. J. MattiellosProtective and Decorative Coatings which gives the chemical composition.

The designation C. 1. refers to the well-known colour index published bythe Society of Dyers and Colorists.

Unless otherwise noted, all percentages are to be considered as being ona weight basis.

Example 1 A one-gallon porcelain pebble mill is charged with 1400 gramsof a liquid grinding medium consisting of 50% dioxane and 50% water. Tothis mixture is added 200 grams of a vinylidene resin plastic producedby the polymerization of styrene, such as polystyrene produced by theBakelite Corporation, and 200 grams of methyl amino anthraquinone (IndoRed RV 20). About 7 lbs. of French flint pebbles are added. Aftermilling for about 45 hours, the mill is discharged and rinsed out withwater. The product and rinse water are collected and filtered. Thefilter cake is then washed, dried and pulverized. One obtains 398 gramsof a plastic color master batch in the form of a fine bright red powderwhich is an excellent dispersion of the coloring matter in thepolystyrene vinylidene resin plastic.

In the above example, for the methyl amino anthraquinone pigment wassubstituted 100 grams of Carbethoxy Pyrazolone Red Toner (M: Fig. 81,page 407), and for the liquid grinding medium was substituted oneconsisting of 50% acetone and 50% water. After processing as indicatedabove, one obtains a fine soft-textured red powder. Similarly otherpigments may be employed, such as Lithosol Red 2B Manganese Toner (M:Fig. 90, page 412), Toluidine Maroon Powder (M: Fig. 83, page 408),Phthalocyanine Green (M: Fig. 144, page 439), Benzidene Yellow Toner (M:Fig. 48, page 391), titanium dioxide, carbon black, and the like. Again,other liquid grinding media may be substituted within the scope of thisinventon to produce a plastc color master batch of excellent quality,and may be composed of water and any one, or combination, of the organicsolvents listed above as suitable for the purposes of this invention, insuch proportions as the preliminary test procedure described above mayindicate.

Example 2 A one-gallon porcelain pebble mill is charged with 200 gramsof Indanthrene Blue (C. I. 1113) and 1200 grams of a liquid grindingmedium consisting of 50% acetone and 50% water. To this mixture is added400 grams of a vinylidene resin plastic produced by the copolymerizationof vinyl chloride and vinyl acetate (vinylite VYHH). About 7 lbs. of #00French flint pebbles are added. After milling for about 70hours, themill is discharged and rinsed out with water. The product and Washliquid are collected and filtered. The filter cake is then washed, driedand pulverized. One obtains around 600 grams of a plastic color masterbatch in the form of a soft-textured blue powder which dissolves easilyinto methyl isobutyl ketone to produce an excellent dispersion.

Other copolymers of the vinylidene monomers are also capable by theprocesses of this invention to be incorporated into plastic color masterbatches. Thus, the following have been embodied in commercial plasticcolor master batches: the copolymer of vinylidene i chloride and vinylchloride, produced by Dow Chemical Company and marketed under the tradename Saran; the copolymer of vinyl chloride and acrylonitrile, producedby Union Carbide & Carbon Corporation, and marketed A one-gallonporcelain pebble mill is charged with 160 grams of Pyrazolone Red Toner(M: Fig. 71, page 402) and 880 grams of a liquid grinding mediumconsisting of dioxane and 20% water. This is mixed well and to themixture is added 240 grams of poly-' merized vinyl chloride powder, suchas produced by B. F. Goodrich under the trade name Geon #101. About 20lbs. of steel balls, averaging /2 in diameter, are added. After millingfor about 45 hours, the mill is discharged and rinsed with water. Theproduct and wash liquid are collected and filtered. The filter cake isthen washed, dried and pulverized. One obtains about 400 grams of aplastic color master batch in the form of a bright, soft-textured redpowder which is a good dispersion as judged by the fineness of itssolution in straight dioxane.

In any of the above Examples 1, 2 and ,3, Turkey Red oil, in amounts offrom 20 to 40 grams, may be added to the liquid grinding medium tofacilitate the filtration and produce a softer color. The Turkey Red oilis a sulfonated oil, is a water-soluble product, and is eliminated inmajor part during the washing and filtration steps.

Other pigments and other liquid grinding media may be employed, asexplained more fully in connection with Example 1.

Example 4 A one-gallon porcelain pebble mill is charged with 75 grams ofCarbethoxy Pyrazolone Red Toner (M: Fig. 81, page 407), 600 grams ofdioxane and 600 grams of water, resulting in a liquid grinding medium of50% dioxane and 50% water. This is mixed well and to the mixture isadded 675 grams of a vinylidene resin plastic consisting of polymerizedvinylidene chloride, such as produced by the Dow Chemical Company and.sold under the trade name Saran B115. About 7 lbs. of #00 French flintpebbles are added. After milling for about 70 hours, the mill isdischarged and rinsed out with water. The product and the wash liquidare collected and filtered. The filter cake is washed, dried andpulverized. One obtains 740 grams of a plastic color master batch in theform of a fine soft dry powder characterized by extreme intensity ofcolor indicating a uniformly high degree of dispersion of pigment in thevinylidene resin plastic.

Other pigments may be substituted for the Red Toner, and other solventsmay be utilized in the liquid grinding medium with excellent results.

Example 5 -milling for about 45 hours, the mill is discharged and rinsedout with water. The product and wash liquid are collected and filtered.The filter cake is then washed, dried and pulverized. One obtains 300grams of a plastic color master batch in the form of a white granularmass which can be readily pulverized for molding purposes.

In the above example, polyacrylonitrile, such as Orlon produced by DuPont, may be substituted for the polymethyl methacrylate, to produceplastic color master batches of excellent quality. In place of titaniumdioxide, a high-grade carbon black, i. e., a fine particle size carbonblack, with either polymethyl methacrylate or polyacrylonitrile, yieldsan excellent quality plastic color master batch. It will be understoodthat other pigments may also be employed in the process of this examplewith very satisfactory results. V

In making the substitutions of plastics and/ or pigments indicated inconnection with the above examples, it is to be understood that theoptimum proportions of the constituents of the liquid grinding mediumneed to be determined in each case by carrying out the test procedurehereinbefore disclosed.

' 7 Example 6 A one-gallon porcelain pebble mill is charged with 108grams of the beta modification of copper phthalocyanine, such as ismarketed under the trade name P'hthaloc'yanine Blue B-4790, and 1500grams of a liquid grinding medium containing 60% acetone and 40% water.This is well mixed and to the mixture is added 216 grams of thecopolymerization product of acrylo nitrile (85%) and vinyl acetate(15%), marketed by the Cheinstrand Corporation under the trade nameAcrilan. About 7- lbs. of French flint pebbles are added. After millingfor about 16 hours, the mill is discharged and rinsed out with water.The product and Wash liquid are collected and filtered. The filter cakeis then washed, dried and pulverized. One obtains about 315 grams of afine soft-textured bright blue powder of high tinctorial value.

Example 7 A one-gallon porcelain pebble mill is charged with 160 gramsRincon Red R-6160 (M: Fig. 91, page 412) and 1520 grams of a liquid.grinding medium containing 88% acetone and 12% water. This is well mixedand to the mixture is added 160 grams of the copolyrnerization productof vinyl chloride (60%) and acrylonitrile (40%), such as is marketed byUnion Carbide & Carbon Corporation under the trade name Vinyon N. About7 lbs; of #00 French flint pebbles are added. After milling for about 16hours, the mill is discharged and rinsed out with water. The product andthe rinse water are collected and filtered. The filter cake is thenwashed, dried and pulverized. One obtains about 315 grams of a brightred soft-textured powder characterized by high intensity of colorindicating a uniformly high degree of dispersion in the vinylidene resinplastic.

Example 8 v about 16 hours, the mill is discharged and rinsed withwater. The product and wash liquid are collected and filtered. Thefilter cake is then washed, dried and pulverized. One obtains about 297grams of a fine White soft-textured powder of high tinctorial value.

Itis in some cases advantageous, as in Example 8 above, to useadditional materials in the milling opera-' tion to overcome certaindifficulties inherent in the solids being; milled, whether in thevinylidene resin plastic or in the pigment. Thus, Where the solids areacid or alkaline to such extent that the acidity or alkalinity, as thecase may be, might adversely affect the quality of the final-product, ormight. seriously corrode the milling equipment, one may overcome thisdifliculty by adding suitable buffering or neutralizing agents which areWater soluble and thus capable of being in major part removed during thewashing operations. Similarly, it is sometimes desirable to add in minorproportions water-soluble wetting agents or other materials to improveor modify the color of the final product just as is done in themanufacture of dry color. Thus, one may add Turkey Red oil, metallicsoaps or other water-soluble pigment modifying agents to the liquidgrinding medium during the grinding operation.

It will be noted from the above examples that with regard to thepercentage of constituents in the liquid grinding medium, one may usefrom as little as approximately 10% to as much as" about by weight,depending upon the liquid organic solvent selected and the particularvinylidene resin plastic to be pigmented. By the test proceduredescribed earlier, one selects the proper ratio of water to liquidorganic solvent that yields in the particular process optimum results.

As indicated hereinbefore, the amount of liquid grinding medium employedin the process is selected to provide a consistency suitable for optimummilling operation. As can be seen, wide variations in the amount ofliquid used is possible, depending upon the amount of solids to bemilled, the type of milling employed and the types of vinylidene resinplastics and pigment to be blended into a plastic color master batch.

The amount of pigment used in the process, and therefore present in thefinal plastic color master batch, may vary from as little as about 1% toas high as approximately by weight, depending on the end use. For mostpurposes as a vinylidene resin plastic color master batch, a range ofapproximately 30% to 70% pigment by weight to the total weight of thecolor master batch is preferred.

It is here pointed out that one may by the process of this inventionmake pigmented vinylidene resin plastic color batches with a mixture ofpigments, in lieu of the single pigment of the above examples, and/orwith a mixture of vinyl resin plastics rather than a single vinylideneresin plastic, in order to obtain desired properties in the pigmentedvinylidene resin plastic color master batch not obtainable with a singlepigment and/ or With a' single vinylidene resin plastic.

The terms color value andchromaticity as used hereinabo've and in theclaims, are terms well known in the art and are employed substantiallyas described and discussed in Handbook of Colorimetry by A. C. Hardy,published bythe Technology Press.

What is claimed is:

1. A process of dispersing pigment in a vinylidene resin plasticwhichcomprises milling pigment and vinylidene resin plastic in a liquidgrinding medium comprising water and a liquid organic water-misciblesolvent in Whichthe vinylidene resin plastic is at least partiallysoluble, the water and solvent being present throughout the millingoperation in such proportions that the liquid grinding. medium. does notdissolve a substantial amount of the vinylidene resin plastic and doesnot cause substantial agglomeration of the vinylidene resin plastic, theliquid grinding medium being present at all times in such amounts as togive a fluidity to the mixture which permits effective milling action,continuing the milling action until a dispersion of pigment invinylidene resin plastic is obtained, and thereafter separating thesolid portion from the liquid portion of the milled mixture.

2. The process of claim 1 wherein pigment and vinylidene resinplasticare each admixed with the liquid grinding medium in particulate form sothat the vinylidene resin plastic particles are caused to becomepigmentreceptive by action of the liquid grinding medium thereon and themilling, action produces impinging contact of pigment particles withpigment-receptive vinylidene resin plastic particles.

3*. The process of claim 1 wherein the vinylidene resin plastic isessentially a polymerization product selected from a class consisting ofpolymers of ethylene, styrene, vinyl chloride, vinylidene chloride,vinyl acetate, vinyl carbazole, acrylonitrile, methylacrylate, methylr'nethacrylate and isobutylene.

4. A vinylidene resin plastic color master batch produced by thepro'cess of claim 1 wherein the amount of pigment is Within a range of30% to 70% of the total weight of the color master batch.

S. A vinylidene resin plastic color master batch consisting essentiallyof pigmented vinylidene resin plastic in the form of dry free-flowingparticles possessing a chromaticity not substantially less than thepigment portion thereof, said particles being readily dispersible in asolvent for the vinylidene resin plastic to yield a colloidal dispersionof pigment in a solution of the vinylidene resin plastic.

6. A process of dispersing pigment in a vinylidene resin plastic whichis essentially a polymerization product selected from a class consistingof polymers of ethylene, styrene, vinyl chloride, vinyl acetate, vinylcarbazole, vinylidene chloride, acrylonitrile, methylacrylate, methylmethacrylate and isobutylene, which comprises milling pigment andvinylidene resin plastic in a liquid grinding medium comprising waterand a liquid organic watermiscible solvent in which the vinylidene resinplastic is at least partially soluble, the water and solvent beingpresent throughout the milling operation in such proportions that theliquid grinding medium does not dissolve a substantial amount of thevinylidene resin plastic and does not cause substantial agglomeration ofthe vinylidene resin plastic, the liquid grinding medium being presentat all times in such amounts as to give a fluidity to the mixture whichpermits effective milling action, continuing the milling action until adispersion of pigment in vinylidene resin plastic is obtained, andthereafter separating the solid portion from the liquid portion of themilled mixture.

7. The process of making a vinylidene resin plastic master color batchwhich comprises milling pigment and vinylidene resin plastic in a liquidgrinding medium comprising water and a liquid organic water-misciblesolvent in which the vinylidene resin plastic is at least partiallysoluble, the water and solvent being present in the liquid grindingmedium in such proportions that it does not dissolve a substantialamount of the vinylidene resin plastie and does not cause substantialagglomeration of the vinylidene resin plastic, the liquid grindingmedium being present in such amounts as to give a fluidity to themixture which permits effective milling action, continuing the millingaction until a vinylidene resin plastic master color batch is obtained,and thereafter filtering the milled mixture, washing the solid portionthereof with water and then drying the solids to produce a vinylideneresin plastic master color batch.

8. The process of claim 7 wherein the vinylidene resin plastic is apolymerization product selected from a class consisting of polymers ofethylene, styrene, vinyl chloride, vinyl acetate, vinyl carbazole,vinylidene chloride, acrylonitrile, methylacrylate, methyl methacrylate,and isobutylene.

9. A vinylidene resin plastic color master batch produced by the processof claim 7 wherein the amount of pigment is within a range of 30% to 70%of the total Weight of the color master batch.

10. The process of making a vinylidene resin plastic master color batchwhich comprises milling pigment and a polymer of vinyl chloride in aliquid grinding medium comprising water and a liquid organicwater-miscible solvent in which the polymer of vinyl chloride is atleast partially soluble, the water and solvent being present in theliquid grinding medium in such proportions that it does not dissolve asubstantial amount of the polymer of vinyl chloride and does not causesubstantial agglomeration of the polymer of vinyl chloride, the liquidgrinding medium being present in such amounts as to give a fluidity tothe mixture which permits effective milling action, continuing themilling action until a master color batch is obtained, and thereafterfiltering the milled mixture, washing the solid portion thereof withwater, and then drying the solids to produce a master color batch.

11. The process of making a vinylidene resin plastic master color batchwhich comprises milling pigment and a polymer of acrylonitrile in aliquid grinding medium comprising water and a liquid organicwater-miscible solvent in which the polymer of acrylonitrile is at leastpartially soluble, the water and solvent being present in the liquidgrinding medium in such proportions that it does not dissolve asubstantial amount of the polymer of acrylonitrile and does not causesubstantial agglomeration of the polymer of acrylonitrile, the liquidgrinding medium being present in such amounts as to give a fluidity tothe mixture which permits effective milling action, continuing themilling action until a master color batch is obtained, and thereafterfiltering the milled mixture, washing the solid portion thereof withwater, and then drying the solids to produce a master color batch.

12. The process of making a vinylidene resin plastic master color batchwhich comprises milling pigment and a copolymer of vinyl chloride andvinyl acetate in a liquid grinding medium. comprising water and a liquidorganic water-miscible solvent in which the copolymer of vinyl chlorideand vinyl acetate is at least partially soluble, the water and solventbeing present in the liquid grinding medium in such proportions that itdoes not dissolve a substantial amount of the copolymer of vinylchloride and vinyl acetate and does not cause substantial agglomerationof the copolymer of vinyl chloride and vinyl acetate, the liquidgrinding medium beingpresent in such amounts as to give a fluidity tothe mixture which permits effective milling action, continuing themilling action until a master color batch is obtained, and thereafterfiltering the milled mixture, washing the solid portion thereof withwater, and then drying the solids to produce a master color batch.

13. The process of making a vinylidene resin plastic master color batchwhich comprises milling pigment and a copolymer of vinyl chloride andacrylonitrile in a liquid grinding medium comprising water and a liquidorganic water-miscible solvent in which the copolymer of vinyl chlorideand acrylonitrile is at least partially soluble, the water and solventbeing present in the liquid grinding medium in such proportions that itdoes not dissolve a substantial amount of the copolymer of vinylchloride and aorylonitrile and does not cause substantial agglomerationof the copolymer of vinyl chloride and acrylonitrile, the liquidgrinding medium being present in such amounts as to give a fluidity tothe mixture which permits effective milling action, continuing themilling action until a master color batch is obtained, and thereafterfiltering the milled mixture, washing the solid portion thereof withwater, and then drying the solids to produce a master color batch.

14. The process of making a vinylidene resin plastic master color batchwhich comprises milling pigment and a copolymer of vinyl acetate andacrylonitrile in a liquid grinding medium comprising water and a liquidorganic water-miscible solvent in which the copolymer of vinyl acetateand acrylonitrile is at least partially soluble, the water and solventbeing present in the liquid grinding medium in such proportions that itdoes not dissolve a substantial amount of the copolymer of vinyl acetateand acrylonitrile and does not cause substantial agglomeration of thecopolymer of vinyl {acetate and acrylonitrile, the

liquid grinding medium being present in such amounts as to give afluidity to the mixture which permits efiective milling action,continuing the milling action until a master color batch is obtained,and thereafter filtering the milled mixture, washing the solid portionthereof with water, and then drying the solids to produce a master colorbatch.

OTHER REFERENCES Hackhs Chemical Dictionary, 3rd ed. Grant page 895,published 1944 by the Blakiston Company, Philadelphia, Pa.

1. A PROCESS OF DISPERSING PIGMENT IN A VINYLIDENE RESIN PLASTIC WHICHCOMPRISES MILLING PIGMENT AND VINYLIDENE RESIN PLASTIC IN A LIQUIDGRINDING MEDIUM COMPRISING WATER AND A LIQUID ORGANIC WATER-MISCIBLESOLVENT IN WHICH THE VINYLIDENE RESIN PLASTIC IS AT LEAST PARTIALLYSOLUBLE, THE WATER AND SOLVENT BEING PRESENT THROUGHOUT THE MILLINGOPERATION IN SUCH PROPORTIONS THAT THE LIQUID GRINDING MEDIUM DOES NOTDISSOLVED A SUBSTANTIAL AMOUNT OF THE VINYLIDENE RESIN PLASTIC AND DOESNOT CAUSE SUBSTANTIAL AGGLOMERATION OF THE VINYLIDENE RESIN PLASTIC, THELIQUID GRINDING MEDIUM BEING PRESENT AT ALL TIMES IN SUCH AMOUNTS AS TOGIVE A FLUIDITY TO THE MIXTURE WHICH PERMITS EFFECTIVE MILLING ACTION,CONTINUING THE MILLING ACTION UNTIL A DISPERSION OF PIGMENT INVINYLIDENE RESIN PLASTIC IS OBTAINED, AND THEREAFTER SEPARATING THESOLID PORTION FROM THE LIQUID PORTION OF THE MILLED MIXTURE.